Many obstetrical interventions used in Latin America, as in other parts of the world, have been shown to be ineffective or harmful, while effective interventions remain underutilized. The goal of this project is to develop and evaluate an intervention intended to implement evidence-based practices among birth attendants in Latin America. The main specific aim of this project is to perform in Argentina and Uruguay a cluster randomized controlled trial of a behavioral intervention that will increase the use of two evidence-based birth practices, the selective use of episiotomies and active management of the third stage of labor. The intervention will be based on the stages of change and organizational change theories and tailored by formative research that will include baseline questionnaires and focus groups. Eighteen hospitals in three urban districts of Argentina and Uruguay will be randomized. Opinion leaders in the 9 intervention hospitals will be identified and trained to develop evidence-based guidelines. They will then diffuse the guidelines by using a multifaceted approach including seminars, academic detailing, reminders, and feedback on utilization rates. The 9 hospitals in the non-intervention group will continue with their standard in-service training activities. The main outcomes to be assessed are the use of episiotomies and of oxytocin during the third stage of labor. Secondary outcomes will be perineal sutures, potspartum hemorrhages, and birth attendants' opinions. The Latin American Center for Perinatology (CLAP) will be the local coordinating center for the trial. In this way, the project endeavors to facilitate capacity building of CLAP and its network of hospitals to perform studies integrating behavioral and clinical research methods. It is also anticipated that the project will contribute to the Global Network by increasing access to a large number of Latin American hospitals that have the capacity to participate in multicentric randomized controlled trials and other clinical studies.